spcadecoder.c

spca5xx video for linux (v4l) driver

	val = 0;
	len = 0;
	if ((i & 0xC0) == 0) {
	    /* code 00 */
	    val = 0;
	    len = 2;
	} else if ((i & 0xC0) == 0x40) {
	    /* code 01 */
	    val = -5;
	    len = 2;
	} else if ((i & 0xC0) == 0x80) {
	    /* code 10 */
	    val = +5;
	    len = 2;
	} else if ((i & 0xF0) == 0xC0) {
	    /* code 1100 */
	    val = -10;
	    len = 4;
	} else if ((i & 0xF0) == 0xD0) {
	    /* code 1101 */
	    val = +10;
	    len = 4;
	} else if ((i & 0xF8) == 0xE0) {
	    /* code 11100 */
	    val = -15;
	    len = 5;
	} else if ((i & 0xF8) == 0xE8) {
	    /* code 11101 */
	    val = +15;
	    len = 5;
	} else if ((i & 0xFC) == 0xF0) {
	    /* code 111100 */
	    val = -20;
	    len = 6;
	} else if ((i & 0xFC) == 0xF4) {
	    /* code 111101 */
	    val = +20;
	    len = 6;
	} else if ((i & 0xF8) == 0xF8) {
	    /* code 11111xxxxxx */
	    is_abs = 1;
	    val = 0;
	    len = 5;
	}
	table[i].is_abs = is_abs;
	table[i].val = val;
	table[i].len = len;
    }
}

static int
pac_decompress_row(struct code_table_t *table, unsigned char *inp,
		   unsigned char *outp, int width)
{
    int col;
    int val;
    int bitpos;
    unsigned char code;


    /* first two pixels are stored as raw 8-bit */
    *outp++ = inp[2];
    *outp++ = inp[3];
    bitpos = 32;

    /* main decoding loop */
    for (col = 2; col < width; col++) {
	/* get bitcode */

	code = getByte(inp, bitpos);
	bitpos += table[code].len;

	/* calculate pixel value */
	if (table[code].is_abs) {
	    /* absolute value: get 6 more bits */
	    code = getByte(inp, bitpos);
	    bitpos += 6;
	    *outp++ = code & 0xFC;
	} else {
	    /* relative to left pixel */
	    val = outp[-2] + table[code].val;
	    *outp++ = CLIP(val);
	}
    }

    /* return line length, rounded up to next 16-bit word */
    return 2 * ((bitpos + 15) / 16);
}
#if 0
static void tv8532_preprocess(struct spca50x_frame *myframe)
{
/* we should received a whole frame with header and EOL marker
in myframe->data and return a GBRG pattern in frame->tmpbuffer
 sequence 2bytes header the Alternate pixels bayer GB 4 bytes
 Alternate pixels bayer RG 4 bytes EOL */
    int width = myframe->hdrwidth;
    int height = myframe->hdrheight;
    int src = 0;
    unsigned char *dst = myframe->tmpbuffer;
    unsigned char *data = myframe->data;
    int i;
    int seq1, seq2;

    /* precompute where is the good bayer line */
    if ((((data[src + 3] + data[src + width + 7]) >> 1) +
	 (data[src + 4] >> 2) + (data[src + width + 6] >> 1)) >=
	(((data[src + 2] + data[src + width + 6]) >> 1) +
	 (data[src + 3] >> 2) + (data[src + width + 5] >> 1))) {
	seq1 = 3;
	seq2 = 4;
    } else {
	seq1 = 2;
	seq2 = 5;
    }
    for (i = 0; i < height / 2; i++) {
	src += seq1;
	memcpy(dst, &myframe->data[src], width);
	src += (width + 3);
	dst += width;
	memcpy(dst, &myframe->data[src], width);
	src += (width + seq2);
	dst += width;
    }
}
#endif
 static inline unsigned char  cabs_diff(unsigned char a,unsigned char b)
{
	return a>=b?a-b:b-a;
};
static void tv8532_preprocess(struct spca50x_frame *myframe)
{
/* we should received a whole frame with header and EOL marker
in myframe->data and return a GBRG pattern in frame->tmpbuffer
 sequence 2bytes header the Alternate pixels bayer GB 4 bytes
 Alternate pixels bayer RG 4 bytes EOL */
	int width = myframe->hdrwidth;
	int height = myframe->hdrheight;
	int src = 0;
	unsigned char *dst = myframe->tmpbuffer;
	unsigned char *data = myframe->data;
	unsigned char * data_ptr;
	int seq1, seq2;
	int sum1=0,sum2=0;
	int height_inc=height/6-1;
	int width_inc=width/6-1;
	int i,j;
	for(i=0;i<4;i++) 
		for(j=0;j<4;j++)
		{
			data_ptr=&data[(i*height_inc)*(width*2+10)+width_inc*j*2];
			sum1+=cabs_diff(data_ptr[3],data_ptr[width + 7])+
				cabs_diff(data_ptr[5],data_ptr[width + 7])+
				cabs_diff(data_ptr[2*width+13],data_ptr[width + 7])+
				cabs_diff(data_ptr[2*width+15],data_ptr[width + 7]);
			sum2+=cabs_diff(data_ptr[width + 6],data_ptr[4])+
				cabs_diff(data_ptr[width + 6],data_ptr[2*width+14])+
				cabs_diff(data_ptr[width + 8],data_ptr[4])+
				cabs_diff(data_ptr[width + 8],data_ptr[2*width+14]);
		
	};
	/* precompute where is the good bayer line */
	if (sum1 <=sum2) {
		seq1 = 3;
		seq2 = 4;
	} else {
		seq1 = 2;
		seq2 = 5;
	};
	for (i = 0; i < height / 2; i++) {
		src += seq1;
		memcpy(dst, &myframe->data[src], width);
		src += (width + 3);
		dst += width;
		memcpy(dst, &myframe->data[src], width);
		src += (width + seq2);
		dst += width;
	}
}
static inline unsigned short getShort(unsigned char *pt)
{
    return ((pt[0] << 8) | pt[1]);
}

static int pixart_decompress(struct spca50x_frame *myframe)
{
/* we should received a whole frame with header and EOL marker
in myframe->data and return a GBRG pattern in frame->tmpbuffer
remove the header then copy line by line EOL is set with 0x0f 0xf0 marker
or 0x1e 0xe1 for compressed line*/
    int width = myframe->hdrwidth;
    int height = myframe->hdrheight;
    unsigned char *outp = myframe->tmpbuffer;
    unsigned char *inp = myframe->data;
    struct code_table_t *table = myframe->decoder->table;
    unsigned short word;
    int row;
    /* skip header */
    inp += 16;
    /* and ask to go at pixel +1 ?? */
    outp++;

    /* iterate over all rows */
    for (row = 0; row < height; row++) {
	word = getShort(inp);
	switch (word) {
	case 0x0FF0:
	    memcpy(outp, inp + 2, width);
	    inp += (2 + width);
	    break;
	case 0x1EE1:
	    inp += pac_decompress_row(table, inp, outp, width);
	    break;

	default:

	    return -1;
	}
	outp += width;
    }

    return 0;
}

/*
#	Decoder for compressed spca561 images			    		#
#	It was developed for "Labtec WebCam Elch 2(SPCA561A)" (046d:0929)	#
#	but it might work with other spca561 cameras				#
*/

static unsigned int bit_bucket;
static unsigned char *input_ptr;

static inline void refill(int *bitfill)
{
    if (*bitfill < 8) {
	bit_bucket = (bit_bucket << 8) | *(input_ptr++);
	*bitfill += 8;
    }
}

static inline int nbits(int *bitfill, int n)
{
    bit_bucket = (bit_bucket << 8) | *(input_ptr++);
    *bitfill -= n;
    return (bit_bucket >> (*bitfill & 0xff)) & ((1 << n) - 1);
}

static inline int _nbits(int *bitfill, int n)
{
    *bitfill -= n;
    return (bit_bucket >> (*bitfill & 0xff)) & ((1 << n) - 1);
}

static int fun_A(int *bitfill)
{
    int ret;
    static int tab[] =
	{ 12, 13, 14, 15, 16, 17, 18, 19, -12, -13, -14, -15, -16, -17,
	-18, -19, -19
    };

    ret = tab[nbits(bitfill, 4)];

    refill(bitfill);
    return ret;
}
static int fun_B(int *bitfill)
{
    static int tab1[] =
	{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 31, 31,
	31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 16, 17,
	18,
	19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30
    };
    static int tab[] =
	{ 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, -5,
	-6, -7, -8, -9, -10, -11, -12, -13, -14, -15, -16, -17, -18, -19
    };
    unsigned int tmp;

    tmp = nbits(bitfill, 7) - 68;
    refill(bitfill);
    if (tmp > 47)
	return 0xff;
    return tab[tab1[tmp]];
}
static int fun_C(int *bitfill, int gkw)
{
    static int tab1[] =
	{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 23, 23, 23, 23, 23, 23,
	23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 12, 13,
	14,
	15, 16, 17, 18, 19, 20, 21, 22
    };
    static int tab[] =
	{ 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, -9, -10, -11,
	-12, -13, -14, -15, -16, -17, -18, -19
    };
    unsigned int tmp;

    if (gkw == 0xfe) {

	if (nbits(bitfill, 1) == 0)
	    return 7;
	else
	    return -8;
    }

    if (gkw != 0xff)
	return 0xff;

    tmp = nbits(bitfill, 7) - 72;
    if (tmp > 43)
	return 0xff;

    refill(bitfill);
    return tab[tab1[tmp]];
}
static int fun_D(int *bitfill, int gkw)
{
    if (gkw == 0xfd) {
	if (nbits(bitfill, 1) == 0)
	    return 12;
	else
	    return -13;
    }

    if (gkw == 0xfc) {
	if (nbits(bitfill, 1) == 0)
	    return 13;
	else
	    return -14;
    }

    if (gkw == 0xfe) {
	switch (nbits(bitfill, 2)) {
	case 0:
	    return 14;
	case 1:
	    return -15;
	case 2:
	    return 15;
	case 3:
	    return -16;
	}

    }

    if (gkw == 0xff) {
	switch (nbits(bitfill, 3)) {
	case 4:
	    return 16;
	case 5:
	    return -17;
	case 6:
	    return 17;
	case 7:
	    return -18;
	case 2:
	    return _nbits(bitfill, 1) ? 0xed : 0x12;
	case 3:
	    *bitfill--;
	    return 18;
	}

	return 0xff;
    }
    return gkw;
}

static int fun_E(int cur_byte, int *bitfill)
{
    static int tab0[] = { 0, -1, 1, -2, 2, -3, 3, -4 };
    static int tab1[] = { 4, -5, 5, -6, 6, -7, 7, -8 };
    static int tab2[] = { 8, -9, 9, -10, 10, -11, 11, -12 };
    static int tab3[] = { 12, -13, 13, -14, 14, -15, 15, -16 };
    static int tab4[] = { 16, -17, 17, -18, 18, -19, 19, -19 };

    if ((cur_byte & 0xf0) >= 0x80) {
	*bitfill -= 4;
	return tab0[(cur_byte >> 4) & 7];
    } else if ((cur_byte & 0xc0) == 0x40) {
	*bitfill -= 5;
	return tab1[(cur_byte >> 3) & 7];

    } else if ((cur_byte & 0xe0) == 0x20) {
	*bitfill -= 6;
	return tab2[(cur_byte >> 2) & 7];

    } else if ((cur_byte & 0xf0) == 0x10) {
	*bitfill -= 7;
	return tab3[(cur_byte >> 1) & 7];

    } else if ((cur_byte & 0xf8) == 8) {
	*bitfill -= 8;
	return tab4[cur_byte & 7];
    }

    return 0xff;
}

static int fun_F(int cur_byte, int *bitfill)
{
    *bitfill -= 5;
    switch (cur_byte & 0xf8) {
    case 0x80:
	return 0;
    case 0x88:
	return -1;
    case 0x90:
	return 1;
    case 0x98:
	return -2;
    case 0xa0:
	return 2;
    case 0xa8:
	return -3;
    case 0xb0:
	return 3;
    case 0xb8:
	return -4;
    case 0xc0:
	return 4;
    case 0xc8:
	return -5;
    case 0xd0:
	return 5;
    case 0xd8:
	return -6;
    case 0xe0:
	return 6;
    case 0xe8:
	return -7;
    case 0xf0:
	return 7;
    case 0xf8:
	return -8;
    }

    *bitfill -= 1;

    switch (cur_byte & 0xfc) {
    case 0x40:
	return 8;
    case 0x44:
	return -9;
    case 0x48: